A plant-based diet reduces postmenopausal hot flashes

Aim

This study investigated the impact of dietary changes on postmenopausal quality of life and vasomotor symptoms, such as hot flashes, which can cause discomfort and reduce quality of life.

It was a follow-on trial from an initial 12-week controlled trial where the cohort followed a plant-based diet including soybeans.

The initial trial showed moderate-to-severe hot flashes reduced by 84% and 59% of participants stopped experiencing hot flashes entirely.

The first trial was held in autumn, and some questioned whether the cool temperature attributed to the results. This updated trial used a two-cohort parallel design (autumn and spring) to rectify that trail limitation.

Method

Social media was used to recruit targeted participants who were postmenopausal women aged 40-65 years who reporting at least two moderate-to-severe hot flashes per day.

Cessation of menstruation >1 and <10 year prior, and willingness to consume a low-fat vegan diet with daily soybeans were inclusion criteria.

After exclusions, 84 met the criteria and were randomly assigned to study groups. Intervention group participants were asked to avoid animal-derived foods, consume minimal oils and fatty foods and consume 86g of cooked soybeans per day, which were provided for intervention participants.

The intervention group were also invited to weekly online 1-hour meetings with a dietitian or researcher to discuss food preparation, dietary challenges, and adherence.

Dietary assessments were done using a 3-day self-reported food record.

Quality of life was reported using the Menopause-Specific Quality if Life (MENQOL) questionnaire.

Hot flashes were self-recorded via mobile application.

Key findings

71 participants completed the main data analysis.

Intervention group mean fat, saturated fat, and cholesterol intake reduced and fibre intake increased (p = .0001), there were no change in the control group.

Body weight decreased by 3.6kg in the intervention group and .2kg in the control group (p < .001). Total hot flash frequency in the intervention group decreased by 78% (p < 0.001) and 39% (p < 0.001) for the control group (between-group p = 0.003). The decrease in moderate-to-severe hot flashes in the intervention group was 88% (from 5.0 to 0.6 per day, p < 0.001), compared with 34% (from 4.4 to 2.9 per day, p < 0.001) among controls (between-group p < 0.001).

Among participants with at least seven (number of events recommended for US Food and Drug Administration trials) moderate-to- severe hot flashes per day at baseline (intervention, n = 8; control, n = 10), hot flashes decreased by 93% (from 10.6 to 0.7 per day) in the intervention group (p < 0.001) and 36% (from 9.0 to 5.8 per day) in the control group (p = 0.01, between-group p < 0.001).

At 12 weeks, the number of intervention group study participants reporting no moderate-to-severe hot flashes increased by 50%.

Vasomotor (p = 0.004), physical (p = 0.01), and sexual (p = 0.03) categories of the MENQOL questionnaires revealed significant between-group differences.

Seasonality had no apparent effect on hot flash frequency.

Conclusion

A reduced-fat vegan diet with daily soybeans led to significant reductions in weight loss and postmenopausal symptoms such as hot flashes.

Change in frequency of severe hot flashes correlated directly with body weight changes (r = 0.36; p = 0.002) and changes in fat intake (r = 0.33; p = 0.01), where changes were inversely linked with carbohydrate (r = −0.35; p = 0.006) and dietary fibre intake (r = −0.29; p = 0.03). In other words, postmenopausal hot flashes are less frequent the more weight and fat intake are reduced, and the more carbohydrates and fibre consumption is increased.

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